1. Field of the Invention
The present invention relates to a motor mounting structure in which a load is applied toward a motor shaft in a direction orthogonal to the shaft, and a drive shaft mounting structure in which a load is applied in a direction orthogonal to the drive shaft.
2. Description of the Related Art
Conventionally, when a motor is mounted to a member to which it is to be mounted, such as a frame or the like, oftentimes an elastic member is disposed between the body of the motor and the member to which the motor is to be mounted, as a measure to isolate vibration. For example, in ink jet printers, a compression coil spring is disposed as an elastic member (see Japanese Patent Application Laid-Open (JP-A) No. 8-17135), and in exposure apparatuses, a damper is disposed as an elastic member. Using an exposure apparatus as an example, conventional technology will be described below.
In a conventional exposure apparatus, a damper 72 such as illustrated in FIG. 9 is used as the aforementioned damper. The damper 72 comprises a cylindrical damper body 73, and an upper retention plate 70 and a lower retention plate 71 that are respectively affixed to an upper surface and a lower surface of the damper body 73.
As shown in FIG. 10C, the damper 72 is disposed between a motor 76, which forwardly rotates and rotates in reverse a timing belt 74, and a mounting plate 80. In FIGS. 10A-10C, the upper and lower retention plates have been omitted to clearly describe the deformation of the damper 72.
A through-hole 72H, through which a shaft 82 of the motor 76 is passed, is formed in the damper 72. Further, an exposure head (not illustrated) that scans in accordance with the rotation and reverse rotation of the timing belt 74 is mounted at the timing belt 74.
To mount the motor 76 at the mounting plate 80, the shaft 82 is passed through the through-hole 72H and screws (not illustrated) are passed through mounting holes 84 formed at lower flanges 77 of the lower retention plate 71 (see FIG. 9), whereby the damper 72 is fixed to the motor 76.
Next, the motor 76 to which the damper 72 is fixed is moved to a mounting portion 81 (see FIG. 10A) of the mounting plate 80, so that a distal end portion of the shaft 82 projects at an outer portion (an upper portion) from an opening 80A formed in advance at the mounting plate 80. Screws (not illustrated) are passed through through-holes 85 formed at upper flanges 79 of the upper retention plate 70 (see FIG. 9) to fix the damper 72 to the mounting plate 80 (see. FIG. 10A).
A pulley 86 is mounted at the distal end portion of the shaft 82 that protrudes from the opening 80A (see FIG. 10B), and the timing belt 74 is trained around the pulley 86 (see FIG. 10C).
However, when a U direction tensile force acts on the timing belt 74, a U direction force is applied to the shaft 82 and a bending moment acts on the motor 76. Accordingly, the motor 76 has been mounted to the mounting plate 80 in a state in which the shaft 82 inclines so that the shaft 82 is no longer orthogonal to an orbital plane S.
Moreover, because an unbalanced load is placed on the timing belt 74 and stress (internal stress) becomes partially larger when the motor 76 is driven in this state, problems such as the durability of the timing belt 74 being poor and an excessive load being placed on the motor 76 have arisen.
Such problems are not restricted to exposure apparatuses and ink jet printers. Even in a common mechanism in which a bending moment is applied by an external force applied to a motor shaft, the motor has been mounted in a state in which the motor shaft is not parallel to a set target mounting direction. For this reason, problems such as excessive stress being applied to the mechanism that transmits a driving force from the shaft and an excessive load being placed on the motor have arisen. Moreover, these problems have not only been limited to a case in which an elastic body has been disposed as a measure to isolate vibration, but have also occurred in common mechanisms in which orientation of the motor shaft and orientation of the drive shaft have been regarded as important.
Taking the above facts into consideration, an object of the present invention is to provide a motor mounting structure with which a motor can be mounted such that a shaft thereof becomes parallel to a set target mounting direction, even when an external force acts on the motor shaft, and to provide a drive shaft mounting structure with which a drive shaft can be mounted such that a shaft thereof becomes parallel to a set target mounting direction, even when an external force acts on the drive shaft.
A motor mounting structure pertaining to a first aspect of the present invention has an elastic member disposed between a motor and a mounting portion to which the motor is mounted, wherein the motor is mounted to the mounting portion via the elastic member, and a motor shaft of the motor has a predetermined angle with respect to a target mounting direction set in advance.
When an external force is not applied to the motor shaft, the motor shaft inclines at a predetermined angle with respect to the target mounting direction that is set in advance. When a force acts on the motor shaft by a driving force transmission mechanism (i.e., a mechanism that transmits a driving force received from the motor shaft) such as a timing belt or the like and a bending moment presumed in advance is applied to the motor, a compressive force acts on the bending side of the elastic member and a tensile force acts on the side opposite the bending side of the elastic member so that the motor shaft becomes parallel to the target mounting direction. The target mounting direction is set, for example, to a direction orthogonal to an orbital plane of the timing belt mounted at a regular position. Further, the predetermined angle is determined in advance giving consideration to parameters such as size of the bending moment, elasticity of the elastic member and so forth.
Accordingly, a mechanism for transmitting a driving force (e.g., a timing pulley and a timing belt mounted at the motor shaft) can be held at a regular position, an unbalanced load is not partially applied to the mechanism for transmitting a driving force and an excessive load is not placed on the motor when the motor is rotated.
In the motor mounting structure of the first aspect of the present invention, the angle of the motor shaft at the time of mounting is preferably adjusted in accordance with a thickness or configuration of the elastic member. Further, the angle of the motor shaft at the time of mounting is adjusted at an inclination angle of the mounting portion with respect to the target mounting direction. Thus, setting of the predetermined angle is easy.
Moreover, in the motor mounting structure of the first aspect of the present invention, the elastic member is preferably provided with a through-hole through which the motor shaft is passed, the through-hole being sufficiently large enough so that the motor shaft does not make contact with an inner wall of the through-hole, and the configuration of the through-hole being formed in a long, substantial ellipse in a direction in which a tensile force acts. Furthermore, a hardness or thickness of the elastic member changes at a tension side and a compression side when a load is applied to the motor shaft.
Still further, in the motor mounting structure of the first aspect of the present invention, the mounting portion is positioned opposite the motor shaft and has a substantially L shape when seen in cross section. The elastic member is disposed so as to make contact with a side surface and a bottom surface of the motor. A hardness of the elastic member changes in correspondence with a difference in compressive force applied thereto when a load is applied to the motor shaft.
In the motor mounting structure of the present invention, wherein the motor mounting structure further comprises a stopper that maintains a posture of the motor shaft on which a moment has acted is preferably provided to abut the housing of the motor.
Accordingly, the motor shaft can be orientated to the target mounting direction, even if the configuration of the elastic member is not strictly formed, so that manufacture of the elastic member becomes remarkably easy. Further, the direction of the motor shaft can be orientated to the target mounting direction by adjusting the position of the stopper, even if the force acting on the motor shaft changes.
A motor mounting structure pertaining to a second aspect of the present invention has a motor and a mounting portion to which the motor is mounted, wherein an end of the mounting portion is joined to a mounting plate by a joint member, another end of the mounting portion is mounted such that an elastic member is disposed between the other end and a press plate, and a motor shaft of the motor has a predetermined angle with respect to a target mounting direction set in advance.
When an external force is not applied to the motor shaft, the motor shaft inclines at a predetermined angle with respect to the target mounting direction that is set in advance. When a force acts on the motor shaft by a driving force transmission mechanism such as a timing belt or the like and a bending moment presumed in advance is applied to the motor, the mounting portion that inclines rotates, together with the motor in the direction in which the bending moment acts, around the joint member disposed at one end of the mounting portion. At this time, because the elastic member is disposed between another end of the mounting portion and the press plate, the motor shaft becomes parallel to the target mounting direction. The target mounting direction is set, for example, to a direction orthogonal to an orbital plane of the timing belt mounted at a regular position. Further, the predetermined angle is determined in advance giving consideration to parameters such as size of the bending moment, elasticity of the elastic member and so forth.
Accordingly, a mechanism for transmitting a driving force can be held at a regular position, an unbalanced load is not partially applied and an excessive load is not placed on the motor at the time the motor is rotated.
In the motor mounting structure of the second aspect of the present invention, the angle of the motor shaft at the time of mounting is preferably adjusted at an inclination angle of the mounting portion with respect to the target mounting direction or adjusted in accordance with dimensions of the elastic member.
Further, in the motor mounting structure of the second aspect of the present invention, the elastic member is not provided with a through-hole for the motor shaft. Moreover, a hardness of the elastic member changes corresponding to a compressive force applied thereto when a load is applied to the motor shaft.
A damper pertaining to another aspect of the present invention is a damper for absorbing vibration between a motor and a motor mounting portion, the damper comprising: a pair of retention plates, one retention plate being mountable to the motor mounting portion and the other retention plate being mountable to the motor; and a resiliently deformable member having opposite ends, each end having a periphery, with one end connected to one of the retention plates and the opposite end connected to the other retention plate, the resiliently deformable member having opposite sides extending from the periphery of one end to the other of the resiliently deformable member, with one side being longer than the opposing side.
Preferably, in the damper of the present invention, the motor includes a motor shaft, and a slot is defined through the retention plates and the resiliently deformable member which receives the motor shaft therethrough when one of the retention plates is mounted to the motor.
With regard to a drive shaft mounting structure pertaining to another aspect of the present invention, in a drive shaft mounting structure provided with a drive shaft, a bearing member disposed around the drive shaft, and an elastic member that is supported at a mounted portion and abuts the peripheral edge of the bearing member, wherein the elastic member is disposed so that the drive shaft has a predetermined angle with respect to a target mounting direction set in advance.
Accordingly, the drive force transmission mechanism (e.g., the timing pulley and timing belt entrained on the drive shaft) is kept at a normal position, and an unbalanced load is not applied partially to the drive force transmission mechanism at the time the drive shaft rotates.
Further, in the drive shaft mounting structure of the present invention, wherein the drive shaft mounting structure further comprises a gear to which the driving force is transmitted is preferably provided at an end of the drive shaft and a pulley that transmits a driving force is preferably provided at another end of the drive shaft.
Accordingly, in a state in which the pulley faces the target mounting direction, the belt trained to the pulley rotates. Thus, an unbalanced load is not partially applied to the belt. Further, an excessive load is not applied to the gear mounted to the drive shaft and the mechanism that transmits a torque to the gear.